Physiology of Circadian Entrainment

Physiological Reviews, Journal Year: 2010, Volume and Issue: 90(3), P. 1063 - 1102

Published: July 1, 2010

Mammalian circadian rhythms are controlled by endogenous biological oscillators, including a master clock located in the hypothalamic suprachiasmatic nuclei (SCN). Since period of this oscillation is ∼24 h, to keep synchrony with environment, need be entrained daily means Zeitgeber (“time giver”) signals, such as light-dark cycle. Recent advances neurophysiology and molecular biology rhythmicity allow better understanding synchronization. In review we cover several aspects mechanisms for photic entrainment mammalian rhythms, retinal sensitivity light novel photopigments well variations retina that contribute regulation physiology. Downstream from retina, examine retinohypothalamic communication through neurotransmitter (glutamate, aspartate, pituitary adenylate cyclase-activating polypeptide) interaction SCN receptors resulting signal transduction pathways neurons, putative neuron-glia interactions. Finally, describe analyze gene expression its importance mechanisms, disorders or diseases related deficits, experimental clinical treatments.

Language: Английский

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Partitioning of Time as an Ecological Resource

Annual Review of Ecology Evolution and Systematics, Journal Year: 2003, Volume and Issue: 34(1), P. 153 - 181

Published: Nov. 1, 2003

▪ Abstract Animal species have evolved different diel activity rhythms that are of adaptive value. Theory suggests temporal partitioning may facilitate coexistence between competitors and predators prey. However, relatively few studies demonstrate a shift is predation- or competition-induced. Recorded shifts usually within the preferred phase animal (day night), although there some inversions to opposite cycle. Temporal not perceived as common mechanism coexistence. This rarity has been variously ascribed theoretical considerations rigidity time-keeping mechanisms, well other physiological anatomical traits constrain patterns. Our decade-long study spiny mice rocky deserts demonstrates that, while factors select for patterns, endogenous rhythmicity be an evolutionary constraint.

Language: Английский

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A human phase-response curve to light

Neuroscience Letters, Journal Year: 1991, Volume and Issue: 133(1), P. 36 - 40

Published: Nov. 1, 1991

Language: Английский

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Masking: History, Definitions, and Measurement

Chronobiology International, Journal Year: 1999, Volume and Issue: 16(4), P. 415 - 429

Published: Jan. 1, 1999

Masking and entrainment are two different processes that result in rhythms physiology behavior. Considering its functional importance, lamentably little study has been devoted to masking compared lavished on entrainment. This paper discusses the origin definition of terminology (positive negative masking, paradoxical masking) methods quantifying masking. How is scored can greatly influence interpretation results.

Language: Английский

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Bright light effects on body temperature, alertness, EEG and behavior

Physiology & Behavior, Journal Year: 1991, Volume and Issue: 50(3), P. 583 - 588

Published: Sept. 1, 1991

Language: Английский

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MORE THAN A MARKER: INTERACTION BETWEEN THE CIRCADIAN REGULATION OF TEMPERATURE AND SLEEP, AGE-RELATED CHANGES, AND TREATMENT POSSIBILITIES

Chronobiology International, Journal Year: 2000, Volume and Issue: 17(3), P. 313 - 354

Published: Jan. 1, 2000

The neurobiological mechanisms of both sleep and circadianregulation have been unraveled partly in the last decades. A network brainstructures, rather than a single locus, is involved arousal state regulation,whereas suprachiasmatic nucleus (SCN) has recognized as key structurefor regulation circadian rhythms. Although most models regulationinclude component, actual mechanism by which circadiantiming system promotes—in addition to homeostatic pressure—transitionsbetween wakefulness remains be elucidated. Little more can bestated presently probable involvement neuronal projections neurohumoralfactors originating SCN. This paper reviews relation among bodytemperature, state, timing proposes thatthe temperature rhythm provides an additional signaling pathwayfor modulation wakefulness. review literatureshows that increased brain associated with type neuronalactivation typical some structures (hypothalamus, basal forebrain),but others (midbrain reticular formation, thalamus).Not only local temperature, but also skin are related activationtype these structures. Warming midbrain hypothalamus, andcerebral cortex (CC). decreasing part coretemperature mainly determined heat loss from extremities,which strongly temperature. As such, alterationsin core over day could modulate activationstate or "preparedness for sleep" arousal-related structures.Body may thus provide third pathway, tosynaptic neurohumoral pathways, sleep.A proposed model effects body on appears fitthe available data better previous hypotheses betweentemperature sleep. Moreover, when age-related thermoregulatoryalterations introduced into model, it adequate descriptionof changes sleep, including shallow awakening closerto nocturnal minimum. Finally, indicates thatappropriately timed direct (passive heating) indirect (bright light, melatonin,physical activity) manipulation profile beneficial disturbed elderly. Althoughsuch procedures viewed researchers merely masking markerfor endogenous rhythm, they fact crucial improvementin elderly subjects. (Chronobiology International,17(3), 313–354, 2000)

Language: Английский

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Extraocular Circadian Phototransduction in Humans

Science, Journal Year: 1998, Volume and Issue: 279(5349), P. 396 - 399

Published: Jan. 16, 1998

Physiological and behavioral rhythms are governed by an endogenous circadian clock. The response of the human clock to extraocular light exposure was monitored measurement body temperature melatonin concentrations throughout cycle before after pulses presented popliteal region (behind knee). A systematic relation found between timing pulse magnitude direction phase shifts, resulting in generation a curve. These findings challenge belief that mammals incapable extraretinal phototransduction have implications for development more effective treatments sleep rhythm disorders.

Language: Английский

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Stability of Melatonin and Temperature as Circadian Phase Markers and Their Relation to Sleep Times in Humans

Journal of Biological Rhythms, Journal Year: 2005, Volume and Issue: 20(2), P. 178 - 188

Published: April 1, 2005

Circadian rhythms of core body temperature and melatonin are commonly used as phase markers the circadian clock. Melatonin is a more stable marker when measured under constant routine conditions. However, little known about variability these less controlled Moreover, there consensus preferred method analysis. The objective this study was to assess various methods calculating in subjects with regular sleep schedules living their natural environment. Baseline data were analyzed from 42 healthy young who studied on at least two occasions. Each hospital admission separated by 3 weeks. Subjects instructed maintain schedule, which monitored for 1 week before logs actigraphy. spent one habituation night conditions prior collecting baseline measurements. rhythm assessed 9 different methods. nadir (Tmin) estimated using both Cleveland Cosine curve fitting procedures, without demasking. Variability between admissions correlation analysis mean absolute difference timing estimates. relationship times onset or offset markers. highly correlated than estimates Tmin. Of estimating Tmin, simple cosine variable. In addition, strongly onset. relative measures had highest coefficients, lowest study-to-study variability, associated onsets. Concordance suggests tendency declining profile be reliable either termination synthesis.

Language: Английский

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Changes in circadian rhythms and sleep quality with aging: Mechanisms and interventions

Neuroscience & Biobehavioral Reviews, Journal Year: 1995, Volume and Issue: 19(4), P. 553 - 571

Published: Dec. 1, 1995

Language: Английский

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Light Exposure Induces Equivalent Phase Shifts of the Endogenous Circadian Rhythms of Circulating Plasma Melatonin and Core Body Temperature in Men*

The Journal of Clinical Endocrinology & Metabolism, Journal Year: 1991, Volume and Issue: 73(2), P. 227 - 235

Published: Aug. 1, 1991

Release of melatonin into the circulation by pineal occurs almost exclusively during nighttime hours. It has been proposed that this daily rhythm, like body temperature, reflects output a central circadian pacemaker in humans. In order to investigate relationship rhythms temperature and humans compare their resetting responses light, we characterized endogenous 24-h profiles these eight young male adults constant routines before after exposure stimulus consisting bright room darkness/sleep. We found time fitted maximum rhythm consistently preceded minimum mean ± se 1.8 0.2 h. Bright-light induced substantial equivalent phase shifts (mean difference phase-shifting response, 0.03 0.32 h), thus maintained usual even light-induced inversion. These results are consistent with hypothesis components both plasma generated single Furthermore, using as reference standard, profile was more reliable marker than onset nocturnal rise (F = 4.48; P < 0.01).

Language: Английский

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